Hello, in medieval times was bog iron ore main source of iron ! My idea is add renewable source of iron in swamps and add new tool (metal rod to searching bog iron) Listen to me, it is very good idea! A bog iron metal have hight content of phosphorus and wrought iron is harder (like mild steel). It will be infinite source of iron. Iron will be respawn (like in nature)
https://www.youtube.com/watch?v=nawca-4dwgy
I like bog iron ore in real life too, i like to make wrought iron